add memcached for macOS

src/SPC/builder/linux/library/libmemcached.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\linux\library;
+
+use SPC\exception\RuntimeException;
+
+/**
+ * gmp is a template library class for unix
+ */
+class libmemcached extends LinuxLibraryBase
+{
+    public const NAME = 'libmemcached';
+
+    public function build()
+    {
+        throw new RuntimeException('libmemcached is currently not supported on Linux platform');
+    }
+}